RUNX3, a novel tumor suppressor, is frequently inactivated in gastric cancer by protein mislocalization

Identification of common genetic factors and immune-related pathways associating more than two autoimmune disorders: implications on risk, diagnosis, and treatment

Autoimmune disorders (ADs) are chronic conditions resulting from failure or breakdown of immunological tolerance, resulting in the host immune system attacking its cells or tissues. Recent studies report shared effects, mechanisms, and evolutionary origins among ADs; however, the possible factors connecting them are unknown. This study attempts to identify gene signatures commonly shared between different autoimmune disorders and elucidate their molecular pathways linking the pathogenesis of these ADs using an integrated gene expression approach. We employed differential gene expression analysis across 19 datasets of whole blood/peripheral blood cell samples with five different autoimmune disorders (rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, Crohn's disease, and type 1 diabetes) to get nine key genes-EGR1, RUNX3, SMAD7, NAMPT, S100A9, S100A8, CYBB, GATA2, and MCEMP1 that were primarily involved in cell and leukocyte activation, leukocyte mediated immunity, IL-17, AGE-RAGE signaling in diabetic complications, prion disease, and NOD-like receptor signaling confirming its role in immune-related pathways. Combined with biological interpretations such as gene ontology (GO), pathway enrichment, and protein-protein interaction (PPI) network, our current study sheds light on the in-depth research on early detection, diagnosis, and prognosis of different ADs.

The m6A-independent role of epitranscriptomic factors in cancer

Protein function alteration and protein mislocalization are cancer hallmarks that drive oncogenesis. N6-methyladenosine (m6A) deposition mediated by METTL3, METTL16, and METTL5 together with the contribution of additional subunits of the m6A system, has shown a dramatic impact on cancer development. However, the cellular localization of m6A proteins inside tumor cells has been little studied so far. Interestingly, recent evidence indicates that m6A methyltransferases are not always confined to the nucleus, suggesting that epitranscriptomic factors may also have multiple oncogenic roles beyond m6A that still represent an unexplored field. To date novel epigenetic drugs targeting m6A modifiers, such as METTL3 inhibitors, are entering into clinical trials, therefore, the study of the potential onco-properties of m6A effectors beyond m6A is required. Here we will provide an overview of methylation-independent functions of the m6A players in cancer, describing the molecular mechanisms involved and the future implications for therapeutics.

RUNX3 pathway signature predicts clinical benefits of immune checkpoint inhibition plus tyrosine kinase inhibition in advanced renal cell carcinoma

BACKGROUND

Checkpoint inhibitor immunotherapy plus tyrosine kinase inhibitor (IO/TKI) have been recently recommended as standard first-line therapy for advanced renal cell carcinoma, while no clinical-available biomarker has been applied. This study aimed to investigate the associations between RUNX3 pathway signature and IO/TKI benefits in renal cell carcinoma (RCC).

METHODS

Two IO/TKI cohorts (ZS-MRCC, JAVELIN-101) and one high-risk localized RCC cohort (ZS-HRRCC) were included. All samples were evaluated by RNA-sequencing, and RUNX Family Transcription Factor 3 (RUNX3) pathway were determined by single sample gene set enrichment analysis. Flow cytometry were applied for immune cell infiltration and function.

RESULTS

RUNX3 signature was elevated in RCC samples, compared non-tumor tissues (P < 0.001). High-RUNX3 signature was associated with shorter progression-free survival (PFS) in both IO/TKI cohorts (ZS-MRCC cohort, P = 0.025; JAVELIN-101 cohort, P = 0.019). RUNX3 signature also predicted IO/TKI benefit in advanced RCC, compared with TKI monotherapy (interaction p = 0.027). RUNX3 signature was associated with decreased number of GZMB + CD8 + T cells (Spearman's ρ=-0.42, P = 0.006), and increased number of PD1 + CD8 + T cells (Spearman's ρ = 0.29, P = 0.072). Moreover, the integration of RUNX3 signature and GZMB expression showed predictive potential for TKI/IO (log-rank P < 0.001). In addition, the predictive value of RUNX3 signature for IO/TKI benefit was restricted in SETD2-wild type patients (log-rank P < 0.001). Finally, a risk score was established by random forest for IO/TKI benefit, showing remarkable predictive potency (Log-rank P < 0.001).

CONCLUSIONS

RUNX3 pathway signature could be a potential predictive biomarker for IO/TKI treatment in advanced RCC, for both prognosis and treatment selection between IO/TKI and TKI monotherapy.

RUNX3 regulates the susceptibility against EGFR-targeted non-small cell lung cancer therapy using 47Sc-conjugated cetuximab

BACKGROUND

Radioimmunotherapy with cetuximab and conjugates with various radioisotopes is a feasible treatment option for different tumor models. Scandium-47 (⁴⁷Sc), one of several β^--particle-emitting radioisotopes, displays favorable physical and chemical properties for conjugation to monoclonal antibodies. However, the therapeutic efficacy of ⁴⁷Sc in preclinical and clinical studies is largely unknown. Given that intrinsic alterations in tumors greatly contribute to resistance to anti-epidermal growth factor receptor (EGFR)-targeted therapy, research on overcoming resistance to radioimmunotherapy using cetuximab is required.

METHODS

⁴⁷Sc was produced by irradiation of a CaCO₃ target at the HANARO research reactor in KAERI (Korea Atomic Energy Research Institute) and prepared by chromatographic separation of the irradiated target. Cetuximab was conjugated with ⁴⁷Sc using the bifunctional chelating agent DTPA. Radiochemical purity was determined using instant thin-layer chromatography. The immunoreactivity of ⁴⁷Sc-DTPA-cetuximab was evaluated using the Lindmo method and an in vitro cell-binding assay. The inhibitory effects of cetuximab and ⁴⁷Sc-DTPA-cetuximab were confirmed using cell growth inhibition and BrdU cell proliferation assays. Differences in protein expression levels between cetuximab- and ⁴⁷Sc-DTPA-cetuximab-treated cells were confirmed using western blotting. Complex formation between RUNX3 and DNA repair components was confirmed using immunoprecipitation and western blotting.

RESULTS

Cetuximab induces cell cycle arrest and cell death in EGFR-overexpressing NSCLC cells. Radiolabeling of cetuximab with ⁴⁷Sc led to increased therapeutic efficacy relative to cetuximab alone. Application of ⁴⁷Sc-DTPA-cetuximab induced DNA damage responses, and activation of RUNX3 significantly enhanced the therapeutic efficacy of ⁴⁷Sc-DTPA-cetuximab. RUNX3 mediated susceptibility to EGFR-targeted NSCLC therapy using ⁴⁷Sc-DTPA-cetuximab via interaction with components of the DNA damage and repair machinery.

CONCLUSIONS

⁴⁷Sc-DTPA-cetuximab promoted cell death in EGFR-overexpressing NSCLC cells by targeting EGFR and inducing DNA damage as a result of β irradiation emitted from the conjugated ⁴⁷Sc. Activation of RUNX3 played a key role in DNA damage and repair processes in response to the ionizing radiation and inhibited cell growth, thus leading to more effective tumor suppression. RUNX3 can potentially moderate susceptibility to ⁴⁷Sc-conjugated cetuximab by modulating DNA damage and repair process mechanisms.

Epigenetic Mechanisms of Aging and Aging-Associated Diseases

Aging is an inevitable outcome of life, characterized by a progressive decline in tissue and organ function. At a molecular level, it is marked by the gradual alterations of biomolecules. Indeed, important changes are observed on the DNA, as well as at a protein level, that are influenced by both genetic and environmental parameters. These molecular changes directly contribute to the development or progression of several human pathologies, including cancer, diabetes, osteoporosis, neurodegenerative disorders and others aging-related diseases. Additionally, they increase the risk of mortality. Therefore, deciphering the hallmarks of aging represents a possibility for identifying potential druggable targets to attenuate the aging process, and then the age-related comorbidities. Given the link between aging, genetic, and epigenetic alterations, and given the reversible nature of epigenetic mechanisms, the precisely understanding of these factors may provide a potential therapeutic approach for age-related decline and disease. In this review, we center on epigenetic regulatory mechanisms and their aging-associated changes, highlighting their inferences in age-associated diseases.

p53 Deficiency-Dependent Oncogenicity of Runx3

The RUNX transcription factors are frequently dysregulated in human cancers, suggesting their potential as attractive targets for drug treatment. However, all three transcription factors have been described as both tumor suppressors and oncogenes, indicating the need to determine their molecular mechanisms of action. Although RUNX3 has long been considered a tumor suppressor in human cancers, several recent studies have shown that RUNX3 is upregulated during the development or progression of various malignant tumors, suggesting it may act as a "conditional" oncogene. Resolving this paradox and understanding how a single gene can exhibit both oncogenic and tumor-suppressive properties is essential for successful drug targeting of RUNX. This review describes the evidence for the activities of RUNX3 in human cancer and proposes an explanation for the duality of RUNX3 involving the status of p53. In this model, p53 deficiency causes RUNX3 to become oncogenic, leading to aberrant upregulation of MYC.

RUNX3 in Stem Cell and Cancer Biology

The runt-related transcription factors (RUNX) play prominent roles in cell cycle progression, differentiation, apoptosis, immunity and epithelial-mesenchymal transition. There are three members in the mammalian RUNX family, each with distinct tissue expression profiles. RUNX genes play unique and redundant roles during development and adult tissue homeostasis. The ability of RUNX proteins to influence signaling pathways, such as Wnt, TGFβ and Hippo-YAP, suggests that they integrate signals from the environment to dictate cell fate decisions. All RUNX genes hold master regulator roles, albeit in different tissues, and all have been implicated in cancer. Paradoxically, RUNX genes exert tumor suppressive and oncogenic functions, depending on tumor type and stage. Unlike RUNX1 and 2, the role of RUNX3 in stem cells is poorly understood. A recent study using cancer-derived RUNX3 mutation R122C revealed a gatekeeper role for RUNX3 in gastric epithelial stem cell homeostasis. The corpora of RUNX3^R122C/R122C mice showed a dramatic increase in proliferating stem cells as well as inhibition of differentiation. Tellingly, RUNX3^R122C/R122C mice also exhibited a precancerous phenotype. This review focuses on the impact of RUNX3 dysregulation on (1) stem cell fate and (2) the molecular mechanisms underpinning early carcinogenesis.

RUNX Family in Hypoxic Microenvironment and Angiogenesis in Cancers

The tumor microenvironment (TME) is broadly implicated in tumorigenesis, as tumor cells interact with surrounding cells to influence the development and progression of the tumor. Blood vessels are a major component of the TME and are attributed to the creation of a hypoxic microenvironment, which is a common feature of advanced cancers and inflamed premalignant tissues. Runt-related transcription factor (RUNX) proteins, a transcription factor family of developmental master regulators, are involved in vital cellular processes such as differentiation, proliferation, cell lineage specification, and apoptosis. Furthermore, the RUNX family is involved in the regulation of various oncogenic processes and signaling pathways as well as tumor suppressive functions, suggesting that the RUNX family plays a strategic role in tumorigenesis. In this review, we have discussed the relevant findings that describe the crosstalk of the RUNX family with the hypoxic TME and tumor angiogenesis or with their signaling molecules in cancer development and progression.

Targeting Undruggable Transcription Factors with PROTACs: Advances and Perspectives

Dysregulation of transcription factors has been implicated in a variety of human diseases. However, these proteins have traditionally been regarded as undruggable and only a handful of them have been successfully targeted by conventional small molecules. Moreover, the development of intrinsic and acquired resistance has hampered the clinical use of these agents. Over the past years, proteolysis-targeting chimeras (PROTACs) have shown great promise because of their potential for overcoming drug resistance and their ability to target previously undruggable proteins. Indeed, several small molecule-based PROTACs have demonstrated superior efficacy in therapy-resistant metastatic cancers. Nevertheless, it remains challenging to identify ligands for the majority of transcription factors. Given that transcription factors recognize short DNA motifs in a sequence-specific manner, multiple novel approaches exploit DNA motifs as warheads in PROTAC design for the degradation of aberrant transcription factors. These PROTACs pave the way for targeting undruggable transcription factors with potential therapeutic benefits.

Hippo in Gastric Cancer: From Signalling to Therapy

The Hippo pathway is one of the most important ones in mammals. Its key functions in cell proliferation, tissue growth, repair, and homeostasis make it the most crucial one to be controlled. Many means have been deployed for its regulation, since this pathway is not only composed of core regulatory components, but it also communicates with and regulates various other pathways, making this signalisation even more complex. Its role in cancer has been studied more and more over the past few years, and it presents YAP/TAZ as the major oncogenic actors. In this review, we relate how vital this pathway is for different organs, and how regulatory mechanisms have been bypassed to lead to cancerous states. Most studies present an upregulation status of YAP/TAZ, and urge the need to target them. A focus is made here on gastric carcinogenesis, its main dysregulations, and the major strategies adopted and tested to counteract Hippo pathway disbalance in this disease. Hippo pathway targeting can be achieved by various means, which are described in this review. Many studies have tested different potential molecules, which are detailed hereby. Though not all tested in gastric cancer, they could represent a real interest.

RUNX3/H3K27me3 Co-Expression Defines a Better Prognosis in Surgically Resected Stage I and Postoperative Chemotherapy-Naive Non-Small-Cell Lung Cancer

The purpose of this study is to investigate the significance of RUNX3/H3K27me3 co-expression in surgically resected non-small-cell lung cancer (NSCLC) patients. Using tissue microarray (TMA), immunohistochemistry, fluorescent double immunostaining, and western blotting, 208 NSCLC and 5 benign pulmonary patients were studied of their expression of runt-related transcription factor 3 (RUNX3), trimethylated histone H3 at lysine 27 (H3K27me3), enhancer of zeste homolog 2 (EZH2), and Ki-67. Apoptotic index in cancerous tissue was evaluated via TdT-mediated dUTP-biotin nick end labeling (TUNEL). The correlation between clinicopathologic parameters and overall survival was determined by Cox regression and Kaplan–Meier survival estimates and log-rank test. GEPIA and KM plotter were used for validation of some survival analyses. As a result, together with other regular prognostic factors, RUNX3/H3K27me3 co-expression was found to be closely correlated with better prognosis in either pTNM-I or POCT-naive NSCLC patients, which might partially result from a higher cancerous apoptotic index. In conclusion, RUNX3/H3K27me3 co-expression defined some specific NSCLC population with better prognosis and longer OS and could probably be used as a biomarker in the prediction of better postoperative outcomes.

Runx3 is required for oncogenic Myc upregulation in p53-deficient osteosarcoma

Osteosarcoma (OS) in human patients is characterized by genetic alteration of TP53. Osteoprogenitor-specific p53-deleted mice (OS mice) have been widely used to study the process of osteosarcomagenesis. However, the molecular mechanisms responsible for the development of OS upon p53 inactivation remain largely unknown. In this study, we detected prominent RUNX3/Runx3 expression in human and mouse p53-deficient OS. Myc was aberrantly upregulated by Runx3 via mR1, a consensus Runx site in the Myc promoter, in a manner dependent on p53 deficiency. Reduction of the Myc level by disruption of mR1 or Runx3 knockdown decreased the tumorigenicity of p53-deficient OS cells and effectively suppressed OS development in OS mice. Furthermore, Runx inhibitors exerted therapeutic effects on OS mice. Together, these results show that p53 deficiency promotes osteosarcomagenesis in human and mouse by allowing Runx3 to induce oncogenic Myc expression.

Infection with a hypervirulent strain of Helicobacter pylori primes gastric cells toward intestinal transdifferentiation

BACKGROUND

Intestinal metaplasia, gastric-to-intestinal transdifferentiation, occurs as a result of the misexpression of certain regulatory factors, leading to genetic reprogramming. Here, we have evaluated the H. pylori-induced expression patterns of these candidate genes.

METHODS

The expression levels of 1) tissue-specific transcription factors (RUNX3, KLF5, SOX2, SALL4, CDX1 and CDX2), 2) stemness factors (TNFRSF19, LGR5, VIL1) and 3) tissue-specific mucins (MUC5AC, MUC2) were evaluated by quantitative real-time PCR in gastric primary cells (GPCs), in parallel with two gastric cancer (MKN45 and AGS) cell lines, up to 96h following H. pylori infection.

RESULTS

Following H. pylori infection of GPCs, RUNX3 declined at 24h post infection (-6.2 ± 0.3) and remained downregulated for up to 96h. Subsequently, overexpression of self-renewal and pluripotency transcription factors, KLF5 (3.6 ± 0.2), SOX2 (7.6 ± 0.5) and SALL4 (4.3 ± 0.2) occurred. The expression of TNFRSF19 and LGR5, demonstrated opposing trends, with an early rise of the former (4.5 ± 0.3) at 8h, and a simultaneous fall of the latter (-1.8 ± 0.5). This trend was reversed at 96h, with the decline in TNFRSF19 (-5.5 ± 0.2), and escalation of LGR5 (2.6 ± 0.2) and VIL1 (1.8 ± 0.3). Ultimately, CDX1 and CDX2 were upregulated by 1.9 and 4.7-fold, respectively. The above scenario was, variably observed in MKN45 and AGS cells.

CONCLUSION

Our data suggests an interdependent gene regulatory network, induced by H. pylori infection. This interaction begins with the downregulation of RUNX3, upregulation of self-renewal and pluripotency transcription factors, KLF5, SOX2 and SALL4, leading to the downregulation of TNFRSF19, upregulation of LGR5 and aberrant expression of intestine-specific transcription factors, potentially facilitating the process of gastric-to-intestinal transdifferentiation.

Runx Transcription Factors in T Cells-What Is Beyond Thymic Development?

Runx proteins (also known as Runt-domain transcription factors) have been studied for a long time as key regulators of cellular differentiation. RUNX2 has been described as essential for osteogenesis, whereas RUNX1 and RUNX3 are known to control blood cell development during different stages of cell lineage specification. However, recent studies show evidence of complex relationships between RUNX proteins, chromatin-modifying machinery, the cytoskeleton and different transcription factors in various non-embryonic contexts, including mature T cell homeostasis, inflammation and cancer. In this review, we discuss the diversity of Runx functions in mature T helper cells, such as production of cytokines and chemokines by different CD4 T cell populations; apoptosis; and immunologic memory acquisition. We then briefly cover recent findings about the contribution of RUNX1, RUNX2 and RUNX3 to various immunologic diseases. Finally, we discuss areas that require further study to better understand the role that Runx proteins play in inflammation and immunity.

Identification and validation of an immune-related gene signature predictive of overall survival in colon cancer

The heterogeneity and complexity of tumor-immune microenvironments lead to diverse immunotherapy effects among colon cancer patients. It is crucial to identify immune microenvironment-related biomarkers and construct prognostic risk models. In this study, the immune and stromal scores of 415 cases from TCGA were calculated using the ESTIMATE algorithm. AXIN2, CCL22, CLEC10A, CRIP2, RUNX3, and TRPM5 were screened and established a prognostic immune-related gene (IRG) signature using by univariate, LASSO, and multivariate Cox regression models. The predicted performance of IRG signature was external validated by GSE39582 (n=519). Stratified survival analysis showed IRG signature was an effective predictor of survival in patients with different clinical characteristics. The protein expression level of six genes was validated by immunohistochemistry analysis. Difference analysis indicated the mutation rate, immune cell of resting NK cells and regulatory T cells infiltration and four immune checkpoints of PD-1, PD-L1, LAG3 and VSIR expression levels in the high-risk group were significantly higher than those in the low-risk group. A nomogram incorporating the gene signatures and clinical factors was demonstrated had a good accuracy (1-, 3-, and 5-year AUC= 0.799, 0.791, 0.738). Our study identified a novel IRG signature, which may provide some references for the clinical precision immunotherapy of patients.

RUNX3 methylation drives hypoxia-induced cell proliferation and antiapoptosis in early tumorigenesis

Inactivation of tumor suppressor Runt-related transcription factor 3 (RUNX3) plays an important role during early tumorigenesis. However, posttranslational modifications (PTM)-based mechanism for the inactivation of RUNX3 under hypoxia is still not fully understood. Here, we demonstrate a mechanism that G9a, lysine-specific methyltransferase (KMT), modulates RUNX3 through PTM under hypoxia. Hypoxia significantly increased G9a protein level and G9a interacted with RUNX3 Runt domain, which led to increased methylation of RUNX3 at K129 and K171. This methylation inactivated transactivation activity of RUNX3 by reducing interactions with CBFβ and p300 cofactors, as well as reducing acetylation of RUNX3 by p300, which is involved in nucleocytoplasmic transport by importin-α1. G9a-mediated methylation of RUNX3 under hypoxia promotes cancer cell proliferation by increasing cell cycle or cell division, while suppresses immune response and apoptosis, thereby promoting tumor growth during early tumorigenesis. Our results demonstrate the molecular mechanism of RUNX3 inactivation by G9a-mediated methylation for cell proliferation and antiapoptosis under hypoxia, which can be a therapeutic or preventive target to control tumor growth during early tumorigenesis.

Elevated expression of RUNX3 co-expressing with EZH2 in esophageal cancer patients from India

Background

Runt related transcription factor3 (RUNX3) is considered as a tumor suppressor gene (TSG) that functions through the TGF-β dependent apoptosis. Promoter methylation of the CpG islands of RUNX3 and overexpression of enhancer of zeste homolog 2 (EZH2) has been suggested to downregulate RUNX3 in cancer.

Methods

Here, we studied the expression of RUNX3 and EZH2 in 58 esophageal tumors along with paired adjacent normal tissue. mRNA levels, protein expressions and cellular localizations of EZH2 and RUNX3 were analyzed using real-time PCR and immunohistochemistry, respectively. DNA methylation was further assessed by the methylation specific-PCR.

Results

Compared to normal tissue, a significant increase in expression of RUNX3 mRNA in 31/57 patient’s tumor tissue (p < 0.04) was observed. The expression of EZH2 was found to be upregulated compared to normal, and a significant positive correlation between EZH2 and RUNX3 expression was observed (p = 0.002). 22 of the 27 unmethylated cases at the promoter region of the RUNX3 had elevated RUNX3 protein expression (p < 0.001).

Conclusion

The data presented in this study provide new insights into the biology of RUNX3 and highlights the need to revisit our current understanding of the role of RUNX3 in cancer.

TrkB Inhibits the BMP Signaling-Mediated Growth Inhibition of Cancer Cells

We have previously observed that tropomyosin receptor kinase B (TrkB) induces breast cancer metastasis by activating both the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) and phosphatidylinositol-3-Kinase (PI3K)/AKT signaling pathways and inhibiting runt-related transcription factor 3 (RUNX3) and kelch-like ECH-associated protein 1 (KEAP1). These studies indicated that TrkB expression is crucial to the pathogenesis of breast cancer. However, how TrkB regulates bone morphogenetic protein (BMP) signaling and tumor suppression is largely unknown. Herein, we report that TrkB is a key regulator of BMP-mediated tumor suppression. TrkB enhances the metastatic potential of cancer cells by promoting cell anchorage-independent growth, migration, and suppressing BMP-2-mediated growth inhibition. TrkB inhibits the BMP-mediated activation of SMAD family member 1 (SMAD1) by promoting the formation of the TrkB/BMP type II receptor complex and suppresses RUNX3 by depleting BMP receptor I (BMPRI) expression. In addition, the knockdown of TrkB restored the tumor-inhibitory effect of BMP-2 via the activation of SMAD1. Moreover, the TrkB kinase activity was required for its effect on BMP signaling. Our study identified a unique role of TrkB in the regulation of BMP-mediated growth inhibition and BMP-2-induced RUNX3 expression.

β-catenin S45F mutation results in apoptotic resistance

Wnt/β-catenin signaling is one of the key cascades regulating embryogenesis and tissue homeostasis; it has also been intimately associated with carcinogenesis. This pathway is deregulated in several tumors, including colorectal cancer, breast cancer, and desmoid tumors. It has been shown that CTNNB1 exon 3 mutations are associated with an aggressive phenotype in several of these tumor types and may be associated with therapeutic tolerance. Desmoid tumors typically have a stable genome with β-catenin mutations as a main feature, making these tumors an ideal model to study the changes associated with different types of β-catenin mutations. Here, we show that the apoptosis mechanism is deregulated in β-catenin S45F mutants, resulting in decreased induction of apoptosis in these cells. Our findings also demonstrate that RUNX3 plays a pivotal role in the inhibition of apoptosis found in the β-catenin S45F mutants. Restoration of RUNX3 overcomes this inhibition in the S45F mutants, highlighting it as a potential therapeutic target for malignancies harboring this specific CTNNB1 mutation. While the regulatory effect of RUNX3 in β-catenin is already known, our results suggest the possibility of a feedback loop involving these two genes, with the CTNNB1 S45F mutation downregulating expression of RUNX3, thus providing additional possible novel therapeutic targets for tumors having deregulated Wnt/β-catenin signaling induced by this mutation.

RUNX3 inhibits the invasion and migration of esophageal squamous cell carcinoma by reversing the epithelial‑mesenchymal transition through TGF‑β/Smad signaling

Runt‑related transcription factor 3 (RUNX3) is a candidate tumor suppressor, and its inactivation may play a crucial role in the carcinogenesis process of numerous cancer types, including esophageal squamous cell carcinoma (ESCC). We previously revealed that RUNX3 inactivation was correlated with lymph node metastasis (LNM) and ESCC recurrence. However, the exact mechanisms of this process are still under investigation. The aim of the present study was to examine the potential roles and underlying molecular mechanisms of RUNX3 in ESCC metastasis and the epithelial‑mesenchymal transition (EMT). According to the results, RUNX3 expression in ESCC tissue was significantly reduced compared with that in adjacent normal tissue (0.50±0.20 vs. 0.83±0.16; P<0.001). In addition, statistical analysis revealed a close association between decreased RUNX3 expression and T status (P=0.027) and LNM (P=0.017) in ESCC patients. Pearson's correlation coefficient analysis was then used to evaluate correlations between RUNX3 and EMT‑related marker expression. The results revealed that RUNX3 expression in ESCC tissues was negatively correlated with the expression of N‑cadherin (r=‑0.429; P<0.01) and Snail (r=‑0.364; P<0.01) and positively correlated with the expression of E‑cadherin (r=0.580; P<0.01). Moreover, Eca109 and EC9706 cell invasion, migration, MMP‑9 expression and EMT were significantly inhibited by RUNX3 overexpression. Notably, further analysis revealed that RUNX3 overexpression markedly inhibited the phosphorylation of Smad2/3; RUNX3‑overexpressing cells also displayed less sensitivity to TGF‑β1‑induced EMT than control cells. Thus, RUNX3 may inhibit the invasion and migration of ESCC cells by reversing EMT through TGF‑β/Smad signaling and may be useful as a therapeutic target.

Complex Interplay between the RUNX Transcription Factors and Wnt/β-Catenin Pathway in Cancer: A Tango in the Night

Cells are designed to be sensitive to a myriad of external cues so they can fulfil their individual destiny as part of the greater whole. A number of well-characterised signalling pathways dictate the cell's response to the external environment and incoming messages. In healthy, well-ordered homeostatic systems these signals are tightly controlled and kept in balance. However, given their powerful control over cell fate, these pathways, and the transcriptional machinery they orchestrate, are frequently hijacked during the development of neoplastic disease. A prime example is the Wnt signalling pathway that can be modulated by a variety of ligands and inhibitors, ultimately exerting its effects through the β-catenin transcription factor and its downstream target genes. Here we focus on the interplay between the three-member family of RUNX transcription factors with the Wnt pathway and how together they can influence cell behaviour and contribute to cancer development. In a recurring theme with other signalling systems, the RUNX genes and the Wnt pathway appear to operate within a series of feedback loops. RUNX genes are capable of directly and indirectly regulating different elements of the Wnt pathway to either strengthen or inhibit the signal. Equally, β-catenin and its transcriptional co-factors can control RUNX gene expression and together they can collaborate to regulate a large number of third party co-target genes.

An effective seven-CpG-based signature to predict survival in renal clear cell carcinoma by integrating DNA methylation and gene expression

AIMS

Currently, using clinicopathological risk factors only is not far from effective to evaluate the risk of disease progression in renal clear cell carcinoma (KIRC) patients. Molecular biomarkers might improve risk stratification of KIRC. DNA methylation occurs the whole process of tumor development and transcriptional disorders are also one of the important characteristics of tumor. Hence, this study aims to develop an effective and independent prognostic signature for KIRC patients by Integrating DNA methylation and gene expression.

MAIN METHODS

Difference analysis was conducted on DNA methylation sites and gene expression data. The Spearman's rank correlation and univariate Cox regression analysis were used to screen out the CpG sites that related with RNAs' expression and KIRC patients' overall survival. Then, a five-CpG-based prognostic classifier was established using LASSO Cox regression method.

KEY FINDINGS

The seven-CpG-based classifier can successfully divide KIRC patients into high-risk from low-risk groups, even after adjustment for standard clinical prognostic factors, such as age, stage, gender and grade. Moreover, the seven-CpG-based signature was more effective as independent prognostic factors than the combined model of these clinical factors. Six differential mRNA genes corresponding to the seven CpG sites are all related to human cancers by functional exploration. The gene functional and pathway enrichment analysis found that genes in immune-related pathways were remarkably different in high and low-risk groups.

SIGNIFICANCE

The new seven-CpG-based signature could helpfully provide insights into the underlying mechanism of KIRC and may be a powerful independent biomarker for predicting of the survival of KIRC patients.

Transcriptome changes induced by RUNX3 in cervical cancer cells in vitro

Runt-related transcription factor 3 (RUNX3) is a member of Runt domain family that is known to play key roles in various different types of tumor. It was recently demonstrated that RUNX3 may also be associated with cervical cancer. The aim of the present study was to investigate the potential association between transcriptome changes and RUNX3 expression in cervical cancer. A RUNX3 overexpression model was constructed using cervical cancer cell lines by RUNX3 plasmid transfection. It was demonstrated that the upregulated expression of RUNX3 inhibited proliferation of cervical cancer cell lines, particularly SiHa cells, and was associated with the expression of the IL-6, PTGS2, FOSL1 and TNF genes. In addition, it was revealed that the TNF and FoxO pathways may also be affected by RUNX3. Therefore, the expression of the RUNX3 gene may be involved in the occurrence and progression of cervical cancer.

Verteporfin targeting YAP1/TAZ-TEAD transcriptional activity inhibits the tumorigenic properties of gastric cancer stem cells

Gastric carcinomas (GC) are heterogeneous tumors, composed of a subpopulation of cluster of differentiation-44 (CD44)+ tumorigenic and chemoresistant cancer stem cells (CSC). YAP1 and TAZ oncoproteins (Y/T) interact with TEA domain family member 1 (TEAD) transcription factors to promote cell survival and proliferation in multiple tissues. Their activity and role in GC remain unclear. This work aimed to analyze Y/T-TEAD activity and molecular signature in gastric CSC, and to assess the effect of verteporfin, a Food and Drug Administration-approved drug preventing Y/T-TEAD interaction, on gastric CSC tumorigenic properties. Y/T-TEAD molecular signature was investigated using bioinformatical (KmPlot database), transcriptomic and immunostaining analyses in patient-derived GC and cell lines. Verteporfin effects on Y/T-TEAD transcriptional activity, CSC proliferation and tumorigenic properties were evaluated using in vitro tumorsphere assays and mouse models of patient-derived GC xenografts. High expressions of YAP1, TAZ, TEAD1, TEAD4 and their target genes were associated with low overall survival in nonmetastatic human GC patients (n = 444). This Y/T-TEAD molecular signature was enriched in CD44+ patient-derived GC cells and in cells resistant to conventional chemotherapy. Verteporfin treatment inhibited Y/T-TEAD transcriptional activity, cell proliferation and CD44 expression, and decreased the pool of tumorsphere-forming CD44⁺ /aldehyde dehydrogenase (ALDH)^high gastric CSC. Finally, verteporfin treatment inhibited GC tumor growth in vivo; the residual tumor cells exhibited reduced expressions of CD44 and ALDH1, and more importantly, they were unable to initiate new tumorspheres in vitro. All these data demonstrate that Y/T-TEAD activity controls gastric CSC tumorigenic properties. The repositioning of verteporfin targeting YAP1/TAZ-TEAD activity could be a promising CSC-based strategy for the treatment of GC.

Chemogenomic study of gemcitabine using Saccharomyces cerevisiae as model cell-molecular insights about chemoresistance

Gemcitabine (GEM) is the drug used as first line to treat pancreatic cancer, one of the most devastating human tumors. This peculiar type of tumor develops resistance to several drugs, including GEM, due to its desmoplastic reaction and other features. The GEM chemoresistance has been investigated at molecular level aiming to find a pathway whose inhibition or activation should overcome it. Through next-generation sequencing was performed a chemogenomic assay of GEM using Saccharomyces cerevisiae as model cell and the results showed that more than 40% of genes related to GEM response in yeast possess unknown or dubious function. We choose two yeast mutants to individually validate the fitness defect results observed by chemogenomic assay, Δhmt1 and Δcsi1, and it was found that in addition to some already described pathways involved in GEM resistance, cells deficient in deneddylation enzyme Cop9 Signalosome Interactor 1 (Csi1p) presented a high sensitivity to GEM. This was confirmed by individual growth analyses of Δcsi1 cells exposed to GEM, and this phenotype was reverted with CSI1 complementation gene. Csi1p is a well-characterized homolog equivalent to human Csn6 subunit of COP9 signalosome (CSN) involved in deneddylation process. We highlighted too that epigenetic alterations, such as methylation mediated by protein arginine methyltransferase 1, play an important role in regulating gemcitabine treatment resistance. Our results point out new unexplored molecular pathways that can be used to overcome GEM resistance: the inhibition of CSN and the arginine methyltransferase activities.

Helicobacter pylori and cytokine gene variants as predictors of premalignant gastric lesions

Gastric cancer remains the third leading cause of mortality from cancer worldwide and carries a poor prognosis, due largely to late diagnosis. The importance of the interaction between Helicobacter pylori (H. pylori) infection, the main risk factor, and host-related genetic factors has been studied intensively in recent years. The genetic predisposition for non-hereditary gastric cancer is difficult to assess, as neither the real prevalence of premalignant gastric lesions in various populations nor the environmental risk factors for cancer progression are clearly defined. For non-cardiac intestinal-type cancer, identifying the factors that modulate the progression from inflammation toward cancer is crucial in order to develop preventive strategies. The role of cytokines and their gene variants has been questioned in regard to non-self-limiting H. pylori gastritis and its evolution to gastric atrophy and intestinal metaplasia; the literature now includes various and non-conclusive results on this topic. The influence of the majority of cytokine single nucleotide polymorphisms has been investigated for gastric cancer but not for preneoplastic gastric lesions. Among the investigated gene variants onlyIL10T-819C, IL-8-251, IL-18RAP917997, IL-22 rs1179251, IL1-B-511, IL1-B-3954, IL4R-398 and IL1RN were identified as predictors for premalignant gastric lesions risk. One of the most important limiting factors is the inhomogeneity of the studies (e.g., the lack of data on concomitant H. pylori infection, methods used to assess preneoplastic lesions, and source population). Testing the modifying effect of H. pylori infection upon the relationship between cytokine gene variants and premalignant gastric lesions, or even testing the interaction between H. pylori and cytokine gene variants in multivariable models adjusted for potential covariates, could increase generalizability of results.

Genetic variants in RUNX3, AMD1 and MSRA in the methionine metabolic pathway and survival in nonsmall cell lung cancer patients

Abnormal methionine dependence in cancer cells has led to methionine restriction as a potential therapeutic strategy. We hypothesized that genetic variants involved in methionine-metabolic genes are associated with survival in nonsmall cell lung cancer (NSCLC) patients. Therefore, we investigated associations of 16,378 common single-nucleotide polymorphisms (SNPs) in 97 methionine-metabolic pathway genes with overall survival (OS) in NSCLC patients using genotyping data from two published genome-wide association study (GWAS) datasets. In the single-locus analysis, 1,005 SNPs were significantly associated with NSCLC OS (p < 0.05 and false-positive report probability < 0.2) in the discovery dataset. Three SNPs (RUNX3 rs7553295 G > T, AMD1 rs1279590 G > A and MSRA rs73534533 C > A) were replicated in the validation dataset, and their meta-analysis showed an adjusted hazards ratio [HR] of 0.82 [95% confidence interval (CI) =0.75-0.89] and pmeta  = 2.86 × 10-6 , 0.81 (0.73-0.91) and pmeta  = 4.63 × 10-4 , and 0.77 (0.68-0.89) and pmeta  = 2.07 × 10-4 , respectively). A genetic score of protective genotypes of these three SNPs revealed an increased OS in a dose-response manner (ptrend  < 0.0001). Further expression quantitative trait loci (eQTL) analysis showed significant associations between these genotypes and mRNA expression levels. Moreover, differential expression analysis further supported a tumor-suppressive effect of MSRA, with lower mRNA levels in both lung squamous carcinoma and adenocarcinoma (p < 0.0001 and < 0.0001, respectively) than in adjacent normal tissues. Additionally, low mutation rates of these three genes indicated the critical roles of these functional SNPs in cancer progression. Taken together, these genetic variants of methionine-metabolic pathway genes may be promising predictors of survival in NSCLC patients.

RUNX3 Promotes the Tumorigenic Phenotype in KGN, a Human Granulosa Cell Tumor-Derived Cell Line

Granulosa cell tumors of the ovary (GCT) are the predominant type of ovarian sex cord/stromal tumor. Although prognosis is generally favorable, the outcome for advanced and recurrent GCT is poor. A better understanding of the molecular pathogenesis of GCT is critical to developing effective therapeutic strategies. Here we have examined the potential role of the runt-related transcription factor RUNX3. There are only two GCT cell lines available. While RUNX3 is silenced in the GCT cell line KGN cells, it is highly expressed in another GCT cell line, COV434 cells. Re-expression of RUNX3 promotes proliferation, anchorage-independent growth, and motility in KGN cells in vitro and tumor formation in mice in vivo. Furthermore, expression of a dominant negative form of RUNX3 decreases proliferation of COV434 cells. To address a potential mechanism of action, we examined expression of cyclin D2 and the CDK inhibitor p27^Kip1, two cell cycle regulators known to be critical determinants of GCT cell proliferation. We found that RUNX3 upregulates the expression of cyclin D2 at the mRNA and protein level, and decreases the level of the p27^Kip1 protein, but not p27^Kip1 mRNA. In conclusion, we demonstrate that RUNX proteins are expressed in GCT cell lines and human GCT specimens, albeit at variable levels, and RUNX3 may play an oncogenic role in a subset of GCTs.

RUNX3 suppresses metastasis and stemness by inhibiting Hedgehog signaling in colorectal cancer

Disabled tumor suppressor genes and hyperactive oncogenes greatly contribute to cell fates during cancer development because of their genetic alterations such as somatic mutations. However, little is known about how tumor suppressor genes react to diverse oncogenes during tumor progression. Our previous study showed that RUNX3 inhibits invasiveness by preventing vascular endothelial growth factor secretion and suppressed endothelial cell growth and tube formation in colorectal cancer (CRC). Hedgehog signaling is crucial for the physiological maintenance and self-renewal of stem cells, and its deregulation is responsible for their tumor development. The mechanisms that inhibit this pathway during proliferation remain poorly understood. Here, we found that the tumor suppressor RUNX3 modulates tumorigenesis in response to cancer cells induced by inhibiting oncogene GLI1 ubiquitination. Moreover, we demonstrated that RUNX3 and GLI1 expression were inversely correlated in CRC cells and tissues. We observed a direct interaction between RUNX3 and GLI1, promoting ubiquitination of GLI1 at the intracellular level. Increased ubiquitination of GLI1 was induced by the E3 ligase β-TrCP. This novel RUNX3-dependent regulatory loop may limit the extent and duration of Hedgehog signaling during extension of the tumor initiation capacity. On the basis of our results, identification of agents that induce RUNX3 may be useful for developing new and effective therapies for CRC.

RUNX family: Oncogenes or tumor suppressors (Review)

Runt-related transcription factor (RUNX) proteins belong to a transcription factors family known as master regulators of important embryonic developmental programs. In the last decade, the whole family has been implicated in the regulation of different oncogenic processes and signaling pathways associated with cancer. Furthermore, a suppressor tumor function has been also reported, suggesting the RUNX family serves key role in all different types of cancer. In this review, the known biological characteristics, specific regulatory abilities and experimental evidence of RUNX proteins will be analyzed to demonstrate their oncogenic potential and tumor suppressor abilities during oncogenic processes, suggesting their importance as biomarkers of cancer. Additionally, the importance of continuing with the molecular studies of RUNX proteins' and its dual functions in cancer will be underlined in order to apply it in the future development of specific diagnostic methods and therapies against different types of cancer.

Signal Transducer and Activator of Transcription (STATs) Proteins in Cancer and Inflammation: Functions and Therapeutic Implication

Signal Transducer and Activator of Transcription (STAT) pathway is connected upstream with Janus kinases (JAK) family protein and capable of integrating inputs from different signaling pathways. Each family member plays unique functions in signal transduction and crucial in mediating cellular responses to different kind of cytokines. STAT family members notably STAT3 and STAT5 have been involved in cancer progression whereas STAT1 plays opposite role by suppressing tumor growth. Persistent STAT3/5 activation is known to promote chronic inflammation, which increases susceptibility of healthy cells to carcinogenesis. Here, we review the role of STATs in cancers and inflammation while discussing current therapeutic implications in different cancers and test models, especially the delivery of STAT3/5 targeting siRNA using nanoparticulate delivery system.

Upregulation of microRNA‑194‑5p inhibits hypopharyngeal carcinoma cell proliferation, migration and invasion by targeting SMURF1 via the mTOR signaling pathway

Hypopharyngeal carcinoma (HPC) is an aggressive malignancy with the worst prognosis among all head and neck cancers. MicroRNAs (miRNAs) are involved in the development of many human cancers, and may function as oncogenes or tumor suppressors. The present study aimed to evaluate the effects of miRNA (miR)-194-5p on the proliferation and invasion of HPC cells and to identify the potential regulatory mechanism. First, miR-194-5p and Smad ubiquitin regulatory factor 1 (SMURF1) expression levels were examined in HPC tissues. Subsequently, to explore the effects of miR-194-5p on SMURF1, a dual-luciferase reporter gene assay was performed to verify the target relationship. To define the role of miR-194-5p in HPC progression, miR-194-5p upregulation and depletion were used to evaluate its effects on cell viability, invasion and migration. SMURF1 silencing and rapamycin [an inhibitor of the mammalian target of rapamycin (mTOR) signaling pathway] treatment were also used to analyze the regulatory mechanism in HPC. Finally, tumor growth was assessed in xenografted tumors in nude mice. SMURF1 was demonstrated to be highly expressed, whereas miR-194-5p was poorly expressed in HPC tissues; SMURF1 was identified as a target gene of miR-194-5p. FaDu hypopharyngeal squamous cell carcinoma cells treated with miR-194-5p mimics exhibited decreased viability, invasion and migration. The results indicated that miR-194-5p may inactivate the mTOR signaling pathway by targeting SMURF1. In addition, the in vivo experiments further verified these regulatory effects. These data suggested that miR-194-5p-targeted SMURF1 inhibition may be involved in the disruption of HPC progression through the repression of the mTOR signaling pathway.

RUNX3 enhances TRAIL-induced apoptosis by upregulating DR5 in colorectal cancer

RUNX3 is frequently inactivated by DNA hypermethylation in numerous cancers. Here, we show that RUNX3 has an important role in modulating apoptosis in immediate response to tumor necrosis factor-related apoptosis-including ligand (TRAIL). Importantly, no combined effect of TRAIL and RUNX3 was observed in non-cancerous cells. We investigated the expression of the death receptors (DRs) DR4 and DR5, which are related to TRAIL resistance. Overexpression of RUNX3 increased DR5 expression via induction of the reactive oxygen species (ROS)-endoplasmic reticulum (ER) stress-effector CHOP. Reduction of DR5 markedly decreased apoptosis enhanced by the combined therapy of TRAIL and RUNX3. Interestingly, RUNX3 induced reactive oxygen species production by inhibiting SOD3 transcription via binding to the Superoxide dismutase 3 (SOD3) promoter. Additionally, the combined effect of TRAIL and RUNX3 decreased tumor growth in xenograft models. Our results demonstrate a direct role for RUNX3 in TRAIL-induced apoptosis via activation of DR5 and provide further support for RUNX3 as an anti-tumor.

Inactivation of RUNX3 protein expression in tongue squamous cell carcinoma and its association with clinicopathological characteristics

The function of runt-related transcription factor 3 (RUNX3) in oral cancer remains controversial. The present study aimed to determine the status of RUNX3 protein expression and its association with clinicopathological characteristics in tongue squamous cell carcinomas (SCC). The present study used three pairs of tongue SCC and non-cancerous tissues to assess RUNX3 protein expression by western blot analysis, and two tongue SCC cell lines to determine RUNX3 protein localization by immunofluorescence and immunocytochemistry. Tissue microarray immunohistochemistry was performed to detect the clinical relevance of RUNX3 in 79 patients with tongue SCC. The results demonstrated that RUNX3 protein expression was reduced in tongue SCC tissues compared with in paired non-cancerous tissues. Similarly, the expression of RUNX3 was low in SCC25 and Cal27 cells, and was predominantly localized to the cytoplasm. In the 79 patients with tongue SCC, RUNX3 protein expression was presented in different manners in carcinoma nests and tumor stroma. RUNX3 in carcinoma nests (nRUNX3) exhibited nuclear positive staining in 24/79 samples, cytoplasmic mislocalization in 41/79 samples and was undetectable in 14/79 samples. RUNX3 in stroma (sRUNX3) exhibited nuclear positive staining in 40/79 samples and nuclear negative staining in 39/79 samples. Negative nRUNX3 expression was significantly associated with lymph node metastasis (P=0.014), clinical stage (P=0.027), and overall and disease-free survival (P=0.008 and P=0.007, respectively). In addition, negative sRUNX3 expression was associated with lymph node metastasis (P=0.003) and clinical stage (P=0.003); however, not with overall survival. The findings of the present study preliminarily suggested that cytoplasmic mislocalization of RUNX3 protein may be a common event in tongue SCC, and that sRUNX3 protein expression may be a potential prognostic biomarker.

Functional characterization of grass carp runt-related transcription factor 3: Involvement in TGF-β1-mediated c-Myc transcription in fish cells

In mammals, both runt-related transcription factor 3 (RUNX3) and c-Myc are the downstream effectors of transforming growth factor-β1 (TGF-β1) signaling to mediate various cellular responses. However, information of their interaction especially in fish is lacking. In the present study, grass carp (Ctenopharyngodon idella) runx3 (gcrunx3) cDNA was cloned and identified. Interestingly, opposing effects of recombinant grass carp TGF-β1 (rgcTGF-β1) on c-myc and runx3 mRNA expression were observed in grass carp periphery blood lymphocytes (PBLs). Parallelly, Runx3 protein levels were enhanced by rgcTGF-β1 in the cells. These findings prompted us to examine whether Runx3 can mediate the inhibition of TGF-β1 on c-myc expression in fish cells. In line with this, overexpression of grass carp Runx3 and Runx3 DN (a dominant-negative form of Runx3) in grass carp kidney cell line (CIK) cells decreased and increased c-myc transcript levels, respectively. Particularly, the regulation of Runx3 and Runx3 DN on c-myc mRNA expression was direct since they were presented in the nucleus without any stimulation. In addition, rgcTGF-β1 alone suppressed c-myc mRNA expression in CIK cells as in PBLs. Moreover, this inhibitory effect was also observed when grass carp Runx3 and Runx3 DN were overexpressed. These results strengthened the role of TGF-β1 signaling in controlling c-myc transcription. Taken together, TGF-β1-mediated c-myc expression was affected at least in part by Runx3, thereby firstly exploring the functional role of Runx3 in TGF-β1 down-regulation on c-myc mRNA expression in fish.

Emerging role of RUNX3 in the regulation of tumor microenvironment

A number of genes have been therapeutically targeted to relieve cancer, but cancer relapse is still a growing issue. The concept that the surrounding tumor environment is critical for the progression of cancer may foster an answer to the issue of cancer malignancy. Runt domain transcription factors (RUNX1, 2, and 3) are evolutionarily conserved and have been intensively studied for their roles in normal development and pathological conditions. During tumor growth, a hypoxic microenvironment and infiltration of the tumor by immune cells are common phenomena. In this review, we briefly introduce the consequences of hypoxia and immune cell infiltration into the tumor microenvironment with a focus on RUNX3 as a critical regulator. Furthermore, based on our current knowledge of the functional role of RUNX3 in hypoxia and immune cell maintenance, a probable therapeutic intervention is suggested for the effective management of tumor growth and malignancy. [BMB Reports 2018; 51(4): 174-181].

RUNX3 Epigenetic Inactivation Is Associated With Estrogen Receptor Positive Breast Cancer

The role of Runt-related transcription factor 3 ( RUNX3) gene in breast cancer remains not fully understood. We studied the correlation between RUNX3 gene promoter methylation and estrogen receptor (ER) expression status in breast cancer. Three breast cancer cell lines and 113 formalin-fixed, paraffin-embedded breast cancer tissue samples were analyzed for RUNX3 expression. Methylation-specific polymerase chain reaction was used to analyze RUNX3 methylation on the samples. Migration and invasion ability were evaluated in MCF7 cell line (RUNX3 methylated) treated with methylation inhibitor 5-Aza-2'-deoxycytidine (5-Aza-CdR) to study the effect of RUNX3 methylation status. Our data showed that the expression of RUNX3 was high in MCF10A but not in MCF7 and SKBR3 cell lines, while the RUNX3 promoter showed hypermethylation in MCF7 but not in MCF10A and SKBR3. In tissues samples, Immunohistochemical (IHC) expression of RUNX3 protein was higher in ER-negative samples than in ER-positive cases, and it was negatively correlated with the methylation status of the RUNX3 gene promoter. Proliferation, migration, and invasion of MCF7 were suppressed when 5-Aza-CdR treated. Also, the hypermethylation status of RUNX3 gene promoter was reversed and RUNX3 expression was increased. In summary, our data suggest that hypermethylation of the RUNX3 gene promoter may play an important role in ER-positive breast tumor progression.

Molecular Signaling in Tumorigenesis of Gastric Cancer

Gastric cancer (GC) is regarded as the fifth most common cancer and the third cause of cancer-related deaths worldwide. Mechanism of GC pathogenesis is still unclear and relies on multiple factors, including environmental and genetic characteristics. One of the most important environmental factors of GC occurrence is infection with Helicobacter pylori that is classified as class one carcinogens. Dysregulation of several genes and pathways play an essential role during gastric carcinogenesis. Dysregulation of developmental pathways such as Wnt/β-catenin signaling, Hedgehog signaling, Hippo pathway, Notch signaling, nuclear factor-kB, and epidermal growth factor receptor have been found in GC. Epithelial-mesenchymal transition, as an important process during embryogenesis and tumorigenesis, is supposed to play a role in initiation, invasion, metastasis, and progression of GC. Although surgery is the main therapeutic modality of the disease, the understanding of biological processes of cell signaling pathways may help to develop new therapeutic targets for GC.

Loss of expression rather than cytoplasmic mislocalization of RUNX3 predicts worse outcome in non-small cell lung cancer

Functional inactivation of human runt-related transcription factor 3 (RUNX3) through mutation or epigenetic silencing has been well-documented in many cancerous entities. In addition to gene mutation and promoter hypermethylation, cytoplasmic mislocalization has emerged as another major manifestation of RUNX3 dysfunction in malignancies including breast, colorectal and gastric cancers. The aim of the present study was to investigate whether patients with non-small cell lung cancer (NSCLC) and different RUNX3 expression patterns would have different overall survival (OS), and the associations between different patterns of clinicopathological parameters and clinical outcome. Expressions of RUNX3 and Ki-67 were immunohistochemically detected in normal lung tissue (n=5) and surgically resected tissues from NSCLC patients (n=188). The optimal cutoff of RUNX3 was determined by X-tile software associated with their survival. Apoptotic index in cancerous tissue was evaluated using the terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labelling method. The prognostic significance of different expression patterns of RUNX3 was determined by means of Kaplan-Meier survival estimates and log-rank tests. It was revealed that loss of RUNX3 expression in NSCLC was correlated with a low cancerous apoptotic index (P<0.001), shorter OS and worse prognosis (P=0.0142), while no statistical difference of apoptotic index (P=0.73) or survival (P=0.3781) was determined between patient subgroups with different localization of RUNX3 expression, which was quite different from the situation demonstrated in other malignancies. In conclusion, loss of expression rather than cytoplasmic mislocalization of RUNX3 predicted worse outcome in NSCLC, which was quite different from what manifested in other cancer types, and thus, the underlying mechanism may deserve further investigation.

RUNX3 regulates renal cell carcinoma metastasis via targeting miR-6780a-5p/E-cadherin/EMT signaling axis

Runt-related transcription factor 3 (RUNX3) is a tumor suppressor in many human solid tumors. In this study, renal cell carcinoma (RCC) microarray analysis showed that the level of RUNX3 expression was lower in RCC tissue than in adjacent normal renal tissues, and was correlated with depth of invasion (pT stage) (P<0.001) and Tumor Node Metastasis (TNM) stage (P<0.001). RUNX3 expression was negatively correlated with poor 5-year overall and disease-free patient survival. RUNX3 suppressed RCC metastasis and invasion and increased levels of E-cadherin, an important marker of epithelial-mesenchymal transition, in vitro and in vivo. RUNX3 also inhibited microRNA-6780a-5p, which directly targeted the E-cadherin 3'untranslated region and decreased its expression. We confirmed that miR-6780a-5p mimics abrogated RUNX3-mediated E-cadherin upregulation and RCC metastasis/invasion inhibition. Thus, RUNX3 targeted the miR-6780a-5p/E-cadherin/EMT signaling axis to suppress renal carcinoma cell migration and invasion. This pathway illustrates a new RUNX3 function and provides potential targets for the treatment of RUNX3 mutant and loss-of-function RCC tumors. RUNX3 may also act as an effective prognostic indicator in RCC.

Knockdown of IARS2 suppressed growth of gastric cancer cells by regulating the phosphorylation of cell cycle-related proteins

The purpose of the article is to investigate the role of IARS2 in proliferation, apoptosis, and cell cycle of gastric cancer (GC) cells in vitro. The IARS2-shRNA lentiviral vector was established and used to infect the GC cell line AGS. qRT-PCR and Western blot were employed to determine the efficiency of IARS2 knockdown. The effects of IARS2 knockdown on cell proliferation, cell clone formation, and cell cycle were assessed by MTT assay, colony formation assay, and flow cytometer analysis, respectively. Finally, a PathScan Antibody Array Kit was used to detect the expression levels of cell cycle-related proteins after IARS2 knockdown in AGS cells to elucidate the underlying mechanisms. Compared with negative control group, IARS2 was significantly knocked down by transfection with lentivirus encoding shRNA of IARS2 in AGS cells. IARS2 knockdown significantly inhibited the proliferation and colony formation ability and induced cycle arrest at G2/M phase of AGS cells. IARS2 knockdown significantly decreased the expression levels of phosphorylation of (p-Smad2), p-SAPK/JUK, cleavage-Caspase-7, and p-TAK1, but increased the expression levels of p-53 and cleavage-PARP in AGS cells compared to shCtrl group. We demonstrated that IARS2 knockdown inhibits proliferation, suppresses colony formation, and causes cell cycle arrest in AGS cells. We also found that IARS2 regulates key molecules of cell apoptosis-related signaling pathway.

Roles of RUNX in Solid Tumors

All RUNX genes have been implicated in the development of solid tumors, but the role each RUNX gene plays in the different tumor types is complicated by multiple interactions with major signaling pathways and tumor heterogeneity. Moreover, for a given tissue type, the specific role of each RUNX protein is distinct at different stages of differentiation. A regulatory function for RUNX in tissue stem cells points sharply to a causal effect in tumorigenesis. Understanding how RUNX dysregulation in cancer impinges on normal biological processes is important for identifying the molecular mechanisms that lead to malignancy. It will also indicate whether restoration of proper RUNX function to redirect cell fate is a feasible treatment for cancer. With the recent advances in RUNX research, it is time to revisit the many mechanisms/pathways that RUNX engage to regulate cell fate and decide whether cells proliferate, differentiate or die.

Runx3 is a key modulator during the epithelial-mesenchymal transition of alveolar type II cells in animal models of BPD

Bronchopulmonary dysplasia (BPD) is a major challenge for premature infants; however, the underlying mechanisms remain unclear. We previously reported that epithelial-mesenchymal transition (EMT) in alveolar type II (AT2) epithelial cells influences the normal alveolar development process. In this study, we wished to examine whether Runx3 is an important factor for BPD by regulating EMT in AT2 cells. In vivo, animal models of BPD were established by placing newborn rats in hyperoxia tanks. Lung tissue and isolated AT2 cells were collected on different days following exposure to oxygen. The pathological changes in lung tissue, alveolar development and Runx3 expression were then investigated. In vitro, RLE-6TN cells were divided into 5 groups as follows: the cont-rol, Runx3, siRunx3, transforming growth factor-β1 (TGF-β1) and Runx3 + TGF-β1 groups, and the biomarkers of EMT were investigated. In the newborn rat model of BPD, Runx3 protein and mRNA levels in both lung tissue and BPD-derived AT2 cells were significantly lower than those in the control group. The correlation between Runx3 protein expression and pulmonary development indicators was analyzed; Runx3 expression positively correlated with the radial alveolar count (RAC) and the percentage of smooth muscle actin-positive secondary septa, but negatively correlated with alveolar wall thickness. EMT was observed in the RLE-6TN cells in which the Runx3 gene was knocked down and follwoing TGF-β1‑induced EMT stimulation; however, TGF-β1 failed to induce EMT in the RLE-6TN cells overexpressing Runx3. On the whole, our data indicte that low Runx3 levels may promote EMT, while high Runx3 levels inhibit TGF-β1-induced EMT. Therefore, we predict that low levels of Runx3 in BPD lung tissue may promote EMT in AT2 cells, thus affecting alveolar development.

RUNX3 plays a tumor suppressor role by inhibiting cell migration, invasion and angiogenesis in oral squamous cell carcinoma

Although aberrant expression of Runt-related transcription factor 3 (RUNX3) contributes to tumor progression and metastasis in a number of carcinomas, the status of RUNX3 and its correlation with prognosis in oral squamous cell carcinomas (OSCC) are still controversial. The aim of present study was to investigate the function of RUNX3 in OSCC and the underlying molecular mechanisms. Tissue microarray (TMA) consisting of 232 OSCC specimens was used to detect the expression of RUNX3 by immunohistochemistry method. The effects of RUNX3 restoration on OSCC cell migration and invasion were determined by wound-healing assay, migration and Matrigel cell invasion assays. The antiangiogenic role of RUNX3 was analyzed by testing proliferation and tube formation of human umbilical vascular endothelial cells (HUVECs) cultured with conditioned medium from RUNX3 transfected OSCC cell lines. The activities of MMP-9 and VEGF in RUNX3 transfected OSCC cell lines were examined by western blot and Elisa methods. RUNX3 expression was reduced in OSCC specimens and significantly associated with tumor size (P=0.002), lymph node statue (P=0.0036) and clinical stage (P=0.0001). Negative expression of RUNX3 correlated with worse 5-year overall and disease-specific survival rates (P=0.0348 and P=0.0301, respectively). Furthermore, we found that RUNX3 restoration suppressed cell migration and invasion through downregulating MMP-9 expression and secretion, and exerted antiangiogenic capability by inhibiting VEGF activity in HN6 and Cal27 cells. These findings suggested that RUNX3 played a tumor suppressor role in OSCC by inhibiting cell migration, invasion and angiogenesis, supporting that it could be a potential therapeutic target for OSCC.

Runx3 inhibits melanoma cell migration through regulation of cell shape change

The transcription factor Runx3 is a known tumor suppressor gene, and its expression is frequently lost in melanoma. However, the potential contribution of the loss of Runx3 expression to melanoma development and progression remains unclear. In this in vitro study, we demonstrated that ectopic Runx3 re-expression in B16-F10 melanoma cells changed the cell shape from elongated and branched to spread and unbranched, which enhanced stress fiber formation, increased the number of mature and fibrillar focal adhesions, and up-regulated fibronectin expression. In association with the cell shape change, the Runx3 re-expression in B16-F10 melanoma cells inhibited cell migration. Moreover, the phenotype of the Runx3 induced cell shape change was partially resembled when the melanoma cells were cultured on a fibronectin-coated coverslip, suggesting that fibronectin may mediate the Runx3 induced cell shape change of the melanoma cells. Taken together, our findings suggest that Runx3 may regulate cell shape to inhibit melanoma cell migration partly through enhancing stress fiber formation and ECM protein production. Our present study provides further evidence for the idea that cell shape change is potentially correlated with melanoma development and progression.

Mislocalization of Runt-related transcription factor 3 results in airway inflammation and airway hyper-responsiveness in a murine asthma model

The Runt-related transcription factor (RUNX) gene family consists of three members, RUNX1, -2 and -3, which heterodimerize with a common protein, core-binding factor β, and contain the highly conserved Runt-homology domain. RUNX1 and -2 have essential roles in hematopoiesis and osteogenesis. Runx3 protein regulates cell lineage decisions in neurogenesis and thymopoiesis. The aim of the present study was to determine the expression features of the Runx3 protein in a murine asthma model. In vivo, Runx3 protein and mRNA were found to be almost equivalently expressed in the murine lung tissue of the control, ovalbumin (OVA) and genistein groups; however, the nuclear Runx3 protein was abated in lung tissue in OVA-immunized and challenged mice. Following treatment with genistein, which is a flavonoid previously demonstrated to decrease airway inflammation in asthma, the allergic airway inflammation and airway hyper-responsiveness were attenuated and the Runx3 protein tended to augment in the nucleus. These results were further determined in vitro. These results indicated that the mislocalization of Runx3 protein is a molecular mechanism of allergic inflammation and airway hyper-responsiveness in a murine asthma model.

UnPAKing RUNX3 functions-Both sides of the coin

Post translational modifications of RUNX3 have been shown to play an important role in directing RUNX3 functions. In this review we highlight the phosphorylation dependent functions of RUNX3 as regulated by PAK1 and its implications on tumorigenesis.

RUNX3 regulates hepatocellular carcinoma cell metastasis via targeting miR-186/E-cadherin/EMT pathway

Runt-related transcription factor 3 (RUNX3) has been reported as a tumor suppressor in some kinds of cancers. In the present study, hepatocellular carcinoma (HCC) microarray analysis showed that RUNX3 expression was significantly lower in HCC tissues compared with that in adjacent non-tumor tissues, and was negatively associated with metastasis and TNM stage. RUNX3 was an independently prognostic factor for 5-year overall and disease-free patient survival. Mechanically, RUNX3 repressed metastasis and invasion of HCC, and increased E-cadherin expression. RUNX3 also repressed microRNA-186 to increase E-cadherin expression. We demonstrated that miR-186 mimics attenuated RUNX3-induced increase of E-cadherin and inhibition of metastasis and invasion. In conclusion, RUNX3 suppressed HCC cell migration and invasion by targeting the miR-186/E-cadherin/EMT pathway. RUNX3 may be recommended as an effective prognostic indicator and therapeutic target for patients with HCC.

Cytoplasmic Localization of RUNX3 via Histone Deacetylase-Mediated SRC Expression in Oxidative-Stressed Colon Cancer Cells

Runt domain transcription factor 3 (RUNX3) is a transcription factor that functions as a tumor suppressor. RUNX3 is frequently inactivated by epigenetic silencing or its protein mislocalization (cytoplasmic localization) in many cancer types. This study investigated whether oxidative stress induces redistribution of RUNX3 from the nucleus to the cytoplasm. The cytoplasmic localization of RUNX3 was associated with oxidative stress-induced RUNX3 phosphorylation at tyrosine residues via SRC activation. Moreover, oxidative stress increased expression of histone deacetylases (HDACs). RUNX3 phosphorylation and SRC expression induced by oxidative stress were inhibited by knockdown of HDAC1, restoring the nuclear localization of RUNX3 under oxidative stress. In conclusion, these results demonstrate that HDAC1- and SRC-mediated phosphorylation of RUNX3 induced by oxidative stress is associated with the cytoplasmic localization of RUNX3 and can lead to RUNX3 inactivation and carcinogenesis. J. Cell. Physiol. 232: 1914-1921, 2017. © 2016 Wiley Periodicals, Inc.